我可以将事件添加到SQLAlchemy中的模型中，该模型在删除项目时触发？

Question

在我的应用程序中，可以通过两种方式删除表“文件”中的行。直接，如session.delete(file)或作为级联删除的结果。我想从我的文件系统中删除该文件，这是数据库行代表的文件，当该行被删除时。有什么办法可以做到吗？

我的模型看起来是这样的：

class File(ModelBase): 
    """Model for the 'files' table. 

    This table holds data about uploaded files. 
    """ 

    __tablename__ = 'files' 

    # Columns 
    id = Column(INTEGER, primary_key=True) 
    uploaded_by_id = Column(INTEGER, ForeignKey(User.__tablename__ + '.id'), 
          nullable=False) 
    path = Column(VARCHAR(255), nullable=False) # The file's name on the server 
    name = Column(VARCHAR(255), nullable=False) # The original file name 
    mime = Column(VARCHAR(75)) 
    size = Column(INTEGER, nullable=False) # File size in bytes 
    uploaded_at = Column(DATETIME, nullable=False) 

    # Relationships 
    uploaded_by = relationship('User', backref='files_uploaded') 

    def __init__(self, uploaded_by, path, name): 

     with ProjectRootContext(): 
      self.uploaded_by = uploaded_by 
      self.path = path 
      self.name = name 
      self.mime = mimetypes.guess_type(path)[0] 
      self.size = os.path.getsize(path) 
      self.uploaded_at = datetime.now() 

    def __repr__(self): 
     return '<File(id=%s,name=%s)>' % (repr(self.id), repr(self.name)) 

    # Factory function for saving an uploaded file 
    @classmethod 
    def from_fieldstorage(cls, uploaded_by, fieldstorage): 
     # ... 

Answer 1

你试过after_delete mapper event了吗？